Conventionally, in order to perform machining with a common numerical control device, a numerical-control machining program in which a movement command for moving a workpiece or a machining tool along a preset path is described is used. The numerical-control machining program is hereinafter referred to as “NC (Numerical Control) machining program”. The NC machining program is created by, for example, commercially-available CAM (Computer Aided Manufacturing) software. The NC machining program is described with, for example, a G-code and a macro character string, which are defined according to the format defined in EIA (Electronic Industries Alliance), or the format defined in ISO (International Standard Organization). In the following descriptions, the format defined in EIA is referred to as “EIA format”, and the format defined in ISO is referred to as “ISO format”. The G-code is a command code described in an NC machining program to execute a command for positioning, linear interpolation, circular interpolation, plane designation, and the like.
The created NC machining program needs to be confirmed in advance before the actual operation. However, it is difficult to confirm the NC machining program by viewing the NC machining program only. Therefore, when an NC machining program is confirmed, a movement command described in the NC machining program is converted to a tool path, and the converted tool path is displayed on a display device, for example. The display device to be used is a CRT (Cathode Ray Tube) device, or a display of the liquid-crystal monitor.
Further, the swept shape of a tool, obtained when the tool moves along the NC machining path, is generated, and the generated shape is removed from the material shape to generate a machining finished shape. The generated machining finished shape is then displayed on a display device such as a CRT device or a display of the liquid-crystal monitor.
In view of the background as described above, Patent Literature 1 discloses a technique of representing a highly-precise model that shows the swept volume of a tool, to improve the space and time efficiency for rendering.
Further, Patent Literature 2 discloses a technique of saving the results of a cutting work as a non-manifold data structure in order that an operator finds an optimum cutting-work procedure through interactive processing. The disclosed technique not only facilitates calculation of a total volume of the actual space during the cutting work, and display of the partially-finished shape, but also, even when the cutting-work procedure is changed to perform the cutting simulation, provides an optimum cutting procedure quickly and easily. In this technique, without performing geometric set operations again, an operator who quickly provides the results of the cutting simulation in correspondence to the changed cutting-work procedure performs logical operations through interactive processing to achieve a smaller amount of calculation.
Furthermore, Patent Literature 3 discloses a technique of simulating a cutting process by using a processing device and a hardware three-dimensional graphics display unit, in order to visualize the shape of a machined workpiece. In this technique, the problems with machining, such as excessively cutting into a die, or insufficiently cutting into a die, can be detected and confirmed before the actual machining. This can reduce time and effort required for the machining.